# Class 12 Physics Chapter 9 Case Study Question Ray Optics and Optical Instruments PDF Download

In Class 12 Boards there will be Case studies and Passage Based Questions will be asked, So practice these types of questions. Study Rate is always there to help you. Free PDF Download of CBSE Class 12 Physics Chapter 9 Ray Optics and Optical Instruments Case Study and Passage Based Questions with Answers were Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Physics Ray Optics and Optical Instruments to know their preparation level.

In CBSE Class 12 Physics Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

# Ray Optics and Optical Instruments Case Study Questions With answers

Here, we have provided case-based/passage-based questions for Class 12 Physics Chapter 9 Ray Optics and Optical Instruments

Case Study/Passage Based Questions

A convex or converging lens is thicker at the center than at the edges. It converges a parallel beam of light on refraction through it. It has a real focus. A convex lens is of three types :
(i) Double convex lens (ii) Plano-convex lens
(iii) Concavo-convex lens. The concave lens is thinner at the center than at the edges. It diverges a parallel beam of light on refraction through it. It has a virtual focus.

Question 1: A point object O is placed at a distance of 0.3 m from a convex lens (focal length 0.2 m) cut into two halves each of which is displaced by 0.0005 m as shown in the figure.

What will be the location of the image?
(a) 30 cm right of lens (b) 60 cm right of lens
(c) 70 cm left of lens (d) 40 cm left of lens

Answer: (b) : Each half of the lens will form an image in the same plane. The optic axes of the lenses are displaced,

Two thin lenses are in contact and the focal length of the combination is 80 cm. If the focal length of one lens is 20 cm, the focal length of the other would be.

(a) –26.7 cm (b) 60 cm
(c) 80 cm (d) 20 cm

A spherical air bubble is embedded in a piece of glass. For a ray of light passing through the bubble, it behaves like a
(a) converging lens
(b) diverging lens
(c) plano-converging lens
(d) plano-diverging lens

Answer: (b) : The bubble behaves like a diverging lens.

Lens used in magnifying glass is
(a) Concave lens
(b) Convex lens
(c) Both (a) and (b)
(d) Neither concave lens nor convex lens

Answer: (b) : Convex lens is used in magnifying glass.

The magnification of an image by a convex lens is positive only when the object is placed
(a) at its focus F
(b) between F and 2F
(c) at 2F
(d) between F and optical center

Answer: (d) between F and optical center

Case Study/Passage Based Questions

A compound microscope is an optical instrument used for observing highly magnified images of tiny objects. The magnifying power of a compound microscope is defined as the ratio of the angle subtended at the eye by the final image to the angle subtended at the eye by the object when both the final image and the object are situated at the least distance of distinct vision from the eye. It can be given that: m = me × mo, where me is magnification produced by eye lens and mo is magnification produced by the objective lens.

Consider a compound microscope that consists of an objective lens of focal length 2.0 cm and an eyepiece of focal length 6.25 cm separated by a distance of 15 cm

The object distance for eye-piece, so that final image is formed at the least distance of distinct vision, will be
(a) 3.45 cm (b) –5 cm
(c) –1.29 cm (d) 2.59 cm

How far from the objective should an object be placed in order to obtain the condition described in Q above?

(a) 4.5 cm (b) 2.5 cm
(c) 1.5 cm (d) 3.0 cm

The intermediate image formed by the objective of a compound microscope is
(a) real, inverted and magnified
(b) real, erect, and magnified
(c) virtual, erect and magnified
(d) virtual, inverted and magnified.

Answer: (a) : The intermediate image formed by the objective of a compound microscope is real, inverted and magnified.

The magnifying power of a compound microscope increases when
(a) the focal length of objective lens is increased and that of eye lens is decreased.
(b) the focal length of eye lens is increased and that of objective lens is decreased.
(c) focal lengths of both objective and eye-piece are increased.
(d) focal lengths of both objective and eye-piece are decreased.

Answer: (d) : Magnifying power of a compound microscope increases when fixed length of both objective and eye-piece are decreased.